Did you know that India, a rising naval power in the Indian Ocean, operates only 16 conventional submarines, while China commands over 50, many equipped with cutting-edge Air-Independent Propulsion (AIP) systems? Submarines are the silent backbone of maritime defence, capable of undetected strikes or deterring adversaries. Yet, India’s underwater fleet struggles to match global leaders like China, the U.S., or even regional rivals like Pakistan, especially as tensions escalate, such as the recent India-Pakistan clash in May 2025. This gap in submarine technology raises critical concerns about India’s naval strength and national security.
This article explores the reasons behind India’s submarine technology lag, its impact, and the steps being taken to bridge the gap. We’ll spotlight key defence companies like Mazagon Dock, L&T, and Data Patterns, delve into projects like Project 75I and INS Arihant, and examine the recent surge in Indian defence stocks amid geopolitical tensions. By the end, you’ll understand the challenges, progress, and what India must do to become a formidable undersea power.
Who Is Affected by India’s Submarine Gap?
India’s submarine technology gap affects multiple stakeholders:
Indian Navy: With just 16 conventional submarines (Sindhughosh, Shishumar, and Kalvari-class) and two nuclear-powered ballistic missile submarines (INS Arihant and Arighaat), the Navy struggles to patrol India’s vast maritime borders. Aging fleets and limited advanced tech reduce operational readiness, especially critical during recent India-Pakistan skirmishes.
Defence Ecosystem: Public sector units (PSUs) like Mazagon Dock and private firms like L&T face delays in tech development, limiting global competitiveness. Smaller players like Data Patterns miss opportunities to innovate in naval electronics.
DRDO: The Defence Research and Development Organisation is overburdened with delayed projects, such as indigenous AIP systems, impacting its credibility.
Indian Citizens: A weaker navy means less deterrence against threats, affecting national security. Taxpayers fund delayed defence projects, expecting timely results, particularly as defence stocks rally due to increased government focus.
Regional Players: China’s 56 submarines, including 17 AIP-equipped Yuan-class, dominate the Indo-Pacific. Pakistan’s AIP-enabled Agosta 90B and upcoming Hangor-class subs, backed by Chinese technology, create a strategic imbalance, especially evident in May 2025’s Operation Sindoor.
Why Indian Submarine Technology Lags
India’s submarine tech lags due to several root causes. Let’s break them down:
a. Late Entry into Submarine Development
India’s submarine program began in 1967 with Soviet Foxtrot-class imports, relying heavily on foreign platforms. Unlike the U.S. or Russia, which started indigenous programs decades earlier, India’s first home-built submarine, INS Arihant, was commissioned only in 2016. This late start meant missing critical R&D cycles.
b. Dependence on Foreign Technology
India’s fleet includes imported platforms like the Russian Kilo-class (Sindhughosh), German Type 209 (Shishumar), and French Scorpène-class (Kalvari). These provide capability but limit self-reliance. Sanctions in the 1990s restricted access to upgrades, exposing vulnerabilities. The leased Russian Akula-class INS Chakra-III, expected in 2025, underscores ongoing reliance.
c. Delays in Key Projects
Major projects face chronic delays:
Project 75: Launched in 1997 to build six Scorpène-class submarines, it was meant to finish by 2017. INS Kalvari was commissioned in 2017, and the sixth, INS Vagsheer, is still in trials as of May 2025.
Project 75I: Envisioned in 1998 for six AIP-equipped diesel-electric subs, it’s stuck in tendering. The first sub is now expected by 2032.
Nuclear Submarines: INS Arihant (2016) and INS Arighaat (2024) are operational, but INS Aridhaman and S4 face delays, with induction expected post-2025.
d. Lack of Indigenous Propulsion & AIP Systems
Air-Independent Propulsion (AIP) allows submarines to remain submerged for weeks, enhancing stealth. Most Indian subs lack AIP, requiring frequent surfacing, which risks detection. DRDO’s phosphoric acid-based AIP is in trials but won’t be fitted on Kalvari-class subs until 2027–28, lagging behind Pakistan’s AIP-equipped subs or China’s Yuan-class.
e. Bureaucracy & PSU Monopoly
Defence shipbuilding has been dominated by PSUs like Mazagon Dock, slowed by bureaucratic red tape. The 2010 Project 75I plan stalled for years over Navy-Ministry disagreements. Unlike China, where state and private firms collaborate, India’s private sector was sidelined until recently.
f. Focus on Surface Fleet
India has prioritized surface ships like destroyers (Visakhapatnam-class) and aircraft carriers (INS Vikrant) over submarines. While surface fleets project power, submarines offer stealth and deterrence, critical in modern warfare and during recent cross-border tensions. This misfocus has underfunded the underwater fleet.
g. Aging Conventional Fleet
Most Indian submarines are 20–30 years old, lacking modern sonar, AIP, or advanced weapons like long-range torpedoes. The Sindhughosh and Shishumar classes, built in the 1980s–90s, have limited stealth compared to China’s Type 039A or Pakistan’s Hangor-class, a concern highlighted during May 2025’s clashes.
Key Defence Companies & Their Roles
India’s defence ecosystem includes PSUs and private firms driving submarine and naval technology. Here’s a detailed look at their contributions, limitations, and future plans:
Public Sector Units (PSUs)
Hindustan Aeronautics Ltd (HAL)
Achievements: HAL is a pioneer in indigenous aircraft, notably the Tejas Light Combat Aircraft (LCA), though it uses imported GE F404 engines. For naval applications, HAL produces ALH Dhruv helicopters for anti-submarine warfare and is exploring seaplane projects. It supplies avionics and structural components for naval aircraft, supporting maritime surveillance. HAL also builds the HTT-40 trainer for the Indian Air Force, indirectly enhancing defence capabilities.
Limitations: HAL relies on GE and Rolls-Royce for jet engines, lacking indigenous fighter-class engine capability (e.g., GE F414 for Tejas Mk2). It has no direct role in submarine development, and projects like Tejas and helicopters have faced delays and cost overruns.
Upcoming: HAL signed a deal with GE in 2024 to manufacture F414 engines in India for Tejas Mk2 and AMCA. It’s collaborating with DRDO to revive the GTX-35VS Kaveri engine program. HAL is also entering the UAV and underwater drone space, potentially supporting naval reconnaissance.Bharat Electronics Ltd (BEL)
Achievements: BEL is a major player in naval electronics, developing radars, sonar, fire-control systems, and communication gear. Its Atulya sonar system, electronic warfare suites, and submarine communication systems are used in Kalvari and Arihant-class subs. BEL exports to over 40 countries, boosting India’s defence profile.
Limitations: BEL primarily integrates systems rather than innovating at the component level. Its PSU structure causes bureaucratic delays, and it depends on imported semiconductors, limiting self-reliance.
Upcoming: BEL is expanding into AIP system controls and integrated bridge systems for submarines. It’s also developing AI-based defence systems and next-gen electronic warfare suites to enhance naval capabilities.Mazagon Dock Shipbuilders Ltd (MDL)
Achievements: MDL is India’s primary submarine builder, constructing all six Scorpène-class (Kalvari-class) submarines under Project 75 with French Naval Group support. It has delivered four subs, with INS Vagir commissioned in 2023. MDL also builds destroyers, corvettes, and stealth frigates, strengthening India’s naval fleet.
Limitations: MDL is a licensed builder, not an original designer, relying on foreign blueprints. Project 75 faced delays, with Kalvari-class subs taking over 15 years from order to commissioning. MDL lacks deep R&D in stealth or nuclear submarine technology.
Upcoming: MDL will lead Project 75I, partnering with Germany’s ThyssenKrupp for six AIP-equipped submarines. It’s also likely to contribute to India’s SSN (nuclear attack submarine) program, enhancing its role in strategic platforms.Garden Reach Shipbuilders & Engineers (GRSE)
Achievements: GRSE builds corvettes and patrol vessels, contributing to India’s maritime ecosystem. While not directly involved in submarines, its naval shipbuilding expertise supports broader defence goals.
Limitations: GRSE has no submarine-building experience, limiting its impact on underwater capabilities.
Upcoming: GRSE may support auxiliary naval projects, potentially aiding submarine maintenance or supply chains.Cochin Shipyard Ltd (CSL)
Achievements: CSL constructs aircraft carriers like INS Vikrant and support vessels, showcasing advanced shipbuilding capabilities.
Limitations: CSL has no direct submarine-building role, focusing on surface ships.
Upcoming: CSL could contribute to submarine maintenance or future naval projects as India expands its underwater fleet.
Private Sector Players
Larsen & Toubro (L&T Defence)
Achievements: L&T is a leading private player, building hull sections for INS Arihant and developing missile launch systems, torpedo launchers, and pressure hulls. Its modular designs and infrastructure expertise make it critical for submarine programs. L&T also collaborates with DRDO on AIP modules.
Limitations: L&T operates as a partner, not a prime contractor, and relies on the Navy and DRDO for design ownership. Its role is secondary to PSUs like MDL.
Upcoming: L&T will co-develop SSNs in the coming decade and is increasing R&D in underwater drones and stealth hull designs, aiming to lead future naval projects.Data Patterns (India) Ltd
Achievements: Data Patterns specializes in high-reliability electronics for air, land, and sea, supplying radar displays, control systems, sonar consoles, and mission computers. It has partnered in RudraM missiles, naval fire-control systems, and coastal surveillance projects, supporting naval operations.
Limitations: As a smaller player compared to BEL or HAL, Data Patterns relies heavily on MoD contracts and has limited production scale. Its R&D budget is smaller than DRDO’s, constraining innovation.
Upcoming: Data Patterns is expanding into space and underwater electronics, working on next-gen radar and sonar systems. It aims to become India’s “Raytheon,” integrating advanced electronics for naval platforms.Paras Defence & Space Technologies
Achievements: Paras provides surveillance systems, drone tech, and EMP protection, supporting naval operations, including submarine defence against electronic threats.
Limitations: Its role is niche, focusing on specific systems rather than broad submarine tech.
Upcoming: Paras is scaling up drone and electronic warfare capabilities, potentially enhancing submarine protection systems.Astra Microwave Products Ltd
Achievements: Astra specializes in RF, microwave, and radar components used in naval platforms, supporting BEL and DRDO in electronic warfare systems and missile radar seekers. Its components are critical for submarine sonar and radar.
Limitations: Astra is a component supplier, not a system integrator, and has no role in strategic propulsion or sonar systems.
Upcoming: Astra is expanding into 5G radar, satellite components, and naval surveillance systems, aiming to strengthen India’s underwater detection capabilities.Bharat Forge (Kalyani Group)
Achievements: Bharat Forge supplies naval gun systems and missile launchers, which could be integrated into future submarine designs.
Limitations: Its focus is on weapons, not core submarine systems like propulsion or hulls.
Upcoming: Bharat Forge is exploring advanced naval weaponry, potentially for next-gen submarines.Tata Advanced Systems Ltd (TASL)
Achievements: TASL develops combat management systems and integrated naval solutions, potentially for submarine command-and-control systems.
Limitations: Its naval role is emerging, with limited submarine-specific contributions.
Upcoming: TASL is expanding into integrated systems, aiming to support future submarine projects.Adani Defence & Aerospace
Achievements: Adani is entering shipbuilding through partnerships, focusing on naval infrastructure.
Limitations: Its naval role is nascent, with no direct submarine involvement.
Upcoming: Adani may contribute to submarine maintenance or auxiliary naval projects.
These companies are pivotal in reducing India’s 60% import dependence, targeting 80% indigenous content for projects like Project 76. Their stocks have seen significant gains in May 2025 due to heightened defence focus.
What India Is Doing to Improve
India is addressing the submarine gap through multiple initiatives, bolstered by recent geopolitical developments:
DRDO’s AIP System: DRDO’s phosphoric acid-based AIP, developed with L&T, is set for integration into INS Kalvari during its 2025 refit. It features 24 fuel cells (13.5–20 kW each) for redundancy, aiming to match global standards by 2028.
Project 75I: This ₹70,000 crore project for six AIP-equipped subs progressed in January 2025, with MDL and ThyssenKrupp selected. The first sub is expected by 2032, featuring advanced sonar and stealth.
Nuclear Submarines: INS Arihant and Arighaat are operational, with INS Aridhaman and S4 nearing completion. Six new SSNs were approved in 2024, with the first due by 2036, boosting strategic deterrence amid regional tensions.
Private Sector Integration: L&T, Data Patterns, and Astra Microwave are being integrated into projects, supported by FDI increases to 74% in defence, fostering innovation.
Additional Scorpène Subs: A ₹33,500 crore deal for three more Kalvari-class subs, potentially with AIP, is nearing approval, strengthening the conventional fleet.
Indigenous Design (Project 76): DRDO and the Navy are designing six conventional subs with 80% indigenous content, targeting completion by 2026, leveraging companies like MDL and L&T.
Surge in Defence Stocks Amid India-Pakistan Tensions: Indian defence stocks have rallied significantly in May 2025, adding over $5 billion in market valuation since the April 22, 2025, Pahalgam terror attack, which killed 26 people. India’s retaliatory Operation Sindoor, launched on May 7, 2025, targeted nine terror hubs in Pakistan and Pakistan-occupied Kashmir, escalating tensions. Pakistan claimed to have shot down five Indian jets, including a Rafale, using Chinese-made J-10C jets and PL-15 missiles, though India denied these claims, calling them disinformation. The conflict, followed by a ceasefire on May 10, 2025, has spotlighted India’s defence sector. Stocks like Mazagon Dock (up 4.6%), HAL (up 2%), BEL (up 2.7%), Bharat Dynamics (up 3%), and Paras Defence (up 5%) surged due to expectations of increased military spending and faster procurement under Make in India. The Nifty India Defence Index rose 3% since the Pahalgam attack, outperforming the Nifty 50’s 1% gain. Analysts attribute the rally to:
Geopolitical Urgency: Operation Sindoor highlighted India’s need for robust defence capabilities, prompting government meetings with manufacturers like Bharat Forge to boost production.
Strong Order Books: HAL’s ₹80,000 crore order book, BEL’s radar and EW contracts, and MDL’s submarine projects ensure revenue visibility.
Policy Support: The FY26 defence budget of ₹6.81 lakh crore, with ₹1.8 lakh crore for capital expenditure, supports indigenous manufacturing.
Export Potential: India’s defence exports, up 23x in eight years, benefit firms like BEL, which exports to 40+ countries.Posts on X reflect bullish sentiment, noting a 20% stock rally after Pakistan’s claims of Indian military threats, with BEL poised for a ₹25,000 crore QRSAM order. However, analysts like Atish Matlawala advise caution for new investors due to high valuations, recommending BEL, MDL, and Bharat Dynamics for their independence from foreign tech, unlike HAL. This surge underscores the urgency of advancing submarine projects to counter regional threats.
How India Compares Globally
India’s submarine fleet lags behind global powers:
India vs. China: China operates 56 submarines, including six nuclear-powered SSNs and 17 AIP-equipped Yuan-class. India’s 16 conventional and two nuclear subs lack AIP and advanced sonar. China’s subs, supporting Pakistan’s military, patrol the Indian Ocean, challenging India’s dominance.
India vs. U.S./Russia: The U.S. has 68 nuclear-powered subs with AI and long-range missiles (Trident: 12,000 km). Russia operates 60 subs, including Yasen-class SSNs with hypersonic missiles. India’s Arihant-class subs carry shorter-range K-15 missiles (700 km).
Comparison Table (as of May 2025):
Country | Total Subs | Conventional (AIP) | Nuclear (SSN/SSBN) | Key Tech |
|---|---|---|---|---|
India | 18 | 16 (0) | 2 (0/2) | Limited AIP, basic sonar |
China | 56 | 41 (17) | 15 (6/9) | Advanced AIP, stealth |
U.S. | 68 | 0 | 68 (50/18) | AI, long-range missiles |
Russia | 60 | 30 (some AIP) | 30 (20/10) | Stealth, hypersonic missiles |
Expert Views & Defence Audits
Experts emphasize urgency:
Vice Admiral Anil Jai Singh (Retd.): “Project 75I is critical, but the seven-year timeline for the first submarine is ambitious. Shipyard capacity at MDL and L&T needs expansion.”
Milind Kulshreshtha (C4I Expert): “AIP is the future of underwater warfare. India’s technology choice will shape strategic partnerships with Europe or Russia.”
Atish Matlawala (SSJ Finance): “BEL, Mazagon Dock, and Bharat Dynamics are strong long-term bets due to robust order books and minimal foreign tech dependence, unlike HAL.”
CAG audits highlight Project 75’s cost overruns (from ₹23,000 crore to ₹40,000 crore) and delays, urging better coordination. A 2023 ORF report stresses resolving tendering issues and empowering private players like L&T and Data Patterns.
Conclusion
India’s submarine technology lags due to late starts, import dependence, project delays, and limited private sector roles. This gap impacts the Navy, defence ecosystem, and national security, especially as India-Pakistan tensions flare, as seen in Operation Sindoor. However, progress is underway: DRDO’s AIP system, Project 75I’s advancement, nuclear submarine programs, and a booming defence sector—evidenced by a $5 billion stock rally—signal momentum. Companies like MDL, L&T, BEL, and Data Patterns, backed by a ₹6.81 lakh crore defence budget, are driving change.
To close the gap, India must fast-track projects, empower private players, and invest in AI, sonar, and underwater drones. The question remains: Can India become a true undersea power by 2035? With focused reforms and collaboration across HAL, BEL, MDL, and emerging players like Data Patterns, bolstered by geopolitical urgency, the answer could be a resounding yes.
Sources
Business Today - Cochin Shipyard, Bharat Forge, HAL, BEL, BDL, GRSE, Mazagon Dock: Why defence stocks are in focus today
- Link: Business Today
- Link: CNBC